Automatic Alignment of the Micropipette for Efficient and Precise Cell Micromanipulation

Abstract

Precise alignment of the micropipette tip is crucial for robotic cell micromanipulation, enabling delicate procedures such as cell transfer, rotation, and immobilization. However, due to the limited field of view and depth perception under high-magnification microscopy, it poses significant challenges in accurately identifying misalignment and effectively controlling micropipette motion for adjustment. This paper comprehensively analyzes and addresses the misalignment problem, particularly that caused by the improper inclination angle of the micropipette holder. A vision-guided robotic control strategy for automatic micropipette alignment is integrated into a 5-degree-of-freedom (5-DOF) micromanipulator, enabling autonomous detection, adjustment, and positioning of the micropipette. The proposed method ensures precise trajectory tracking and compensates for geometric uncertainties introduced by fabrication or installation errors. Experimental validation demonstrates that the proposed system achieved a mean absolute error below 3 µm for positioning the tip of the micropipette at the focal plane during the procedure of adjustment. Meanwhile, the robotic method required significantly less time to stably rotate the micropipette compared to manual operation for cell manipulation. The vertical alignment error was less than 3 µm along a 250 µm micropipette tip segment. These results confirm that the proposed approach significantly enhances speed, accuracy, and repeatability in micropipette-based micro-manipulation, providing a robust solution for high-throughput biological experiments and clinical applications.